The present invention relates to cement systems that combine a hydrating cement system, and more particularly cement-based systems that comprise chemically bonded ceramics of calcium aluminates and/or calcium silicates, and traditional glass ionomer cement materials. The inventive systems are suitable for use as biomaterials, for example, as implants and, in a specific embodiment, as implants in dental applications.
Materials such as dental materials and other implants desirably interact with the human body and therefore should be as bioactive or biocompatible as possible. Other properties that are specifically required for dental cement materials include good handling ability with simple applicability, molding ability that permits good shaping, hardening/ solidification that is sufficiently rapid for use within minutes, especially without detrimental heat generation, and that provides serviceability directly following therapy, corrosion resistance, good bonding to a natural biological surface such as a tooth and/or another implant, radio-opacity, excellent long term properties, and good aesthetics. Materials fulfilling one or more of these desirable properties are known in the art and have been described in, e.g., WO 90/11066, EP 559 627 A2, WO 00/21489, WO 01/76534, WO 01/76535, WO 2003/041662, and WO 2004/037215.
Additionally, WO 2005/039508 discloses a two-step system for chemically bonded ceramic (CBC) materials, preferably a dental filling material or an implant material. The system includes an initial working part system to provide for improved early-age properties and a second system to provide for improved end-product properties, including bioactivity. The initial working part system comprises polyacrylic acid and/or a salt or ester thereof, or other polycarboxylic acid, copolymer thereof, or polycarboxylate (i.e., a salt or ester) thereof, and a glass powder. Such an initial working part system is traditionally described as a glass ionomer cement system. The second system is of the hydrating cement system type, in particular, reactive cement-based systems that comprise chemically bonded ceramics of aluminates or silicates. WO 2005/039508 specifically discloses material compositions that provide a hybrid material of calcium aluminate or calcium silicate and glass ionomer cement to form a bioactive dental cement system. However, the prior art system exhibits lower mechanical strength than conventional high strength glass ionomer cement systems and also higher opacity for visible light compared to modern high strength glass ionomer cement systems. Accordingly, further improvements in obtaining a combination of good properties as described above, as well as bioactive features, are desired.